Commit Graph

138 Commits

Author SHA1 Message Date
Michael Sproul
aaebf72835 Remove recursion from DB state lookup 2022-05-27 16:05:55 +10:00
Michael Sproul
b774a1c3f1 Use schema v20 for tree-states 2022-05-24 10:37:39 +10:00
Michael Sproul
e436035c52 Merge remote-tracking branch 'origin/unstable' into tree-states 2022-05-24 10:01:05 +10:00
Michael Sproul
bcdd960ab1 Separate execution payloads in the DB (#3157)
## Proposed Changes

Reduce post-merge disk usage by not storing finalized execution payloads in Lighthouse's database.

⚠️ **This is achieved in a backwards-incompatible way for networks that have already merged** ⚠️. Kiln users and shadow fork enjoyers will be unable to downgrade after running the code from this PR. The upgrade migration may take several minutes to run, and can't be aborted after it begins.

The main changes are:

- New column in the database called `ExecPayload`, keyed by beacon block root.
- The `BeaconBlock` column now stores blinded blocks only.
- Lots of places that previously used full blocks now use blinded blocks, e.g. analytics APIs, block replay in the DB, etc.
- On finalization:
    - `prune_abanonded_forks` deletes non-canonical payloads whilst deleting non-canonical blocks.
    - `migrate_db` deletes finalized canonical payloads whilst deleting finalized states.
- Conversions between blinded and full blocks are implemented in a compositional way, duplicating some work from Sean's PR #3134.
- The execution layer has a new `get_payload_by_block_hash` method that reconstructs a payload using the EE's `eth_getBlockByHash` call.
   - I've tested manually that it works on Kiln, using Geth and Nethermind.
   - This isn't necessarily the most efficient method, and new engine APIs are being discussed to improve this: https://github.com/ethereum/execution-apis/pull/146.
   - We're depending on the `ethers` master branch, due to lots of recent changes. We're also using a workaround for https://github.com/gakonst/ethers-rs/issues/1134.
- Payload reconstruction is used in the HTTP API via `BeaconChain::get_block`, which is now `async`. Due to the `async` fn, the `blocking_json` wrapper has been removed.
- Payload reconstruction is used in network RPC to serve blocks-by-{root,range} responses. Here the `async` adjustment is messier, although I think I've managed to come up with a reasonable compromise: the handlers take the `SendOnDrop` by value so that they can drop it on _task completion_ (after the `fn` returns). Still, this is introducing disk reads onto core executor threads, which may have a negative performance impact (thoughts appreciated).

## Additional Info

- [x] For performance it would be great to remove the cloning of full blocks when converting them to blinded blocks to write to disk. I'm going to experiment with a `put_block` API that takes the block by value, breaks it into a blinded block and a payload, stores the blinded block, and then re-assembles the full block for the caller.
- [x] We should measure the latency of blocks-by-root and blocks-by-range responses.
- [x] We should add integration tests that stress the payload reconstruction (basic tests done, issue for more extensive tests: https://github.com/sigp/lighthouse/issues/3159)
- [x] We should (manually) test the schema v9 migration from several prior versions, particularly as blocks have changed on disk and some migrations rely on being able to load blocks.

Co-authored-by: Paul Hauner <paul@paulhauner.com>
2022-05-12 00:42:17 +00:00
Michael Sproul
375e2b49b3 Conserve disk space by raising default SPRP (#3137)
## Proposed Changes

Increase the default `--slots-per-restore-point` to 8192 for a 4x reduction in freezer DB disk usage.

Existing nodes that use the previous default of 2048 will be left unchanged. Newly synced nodes (with or without checkpoint sync) will use the new 8192 default. 

Long-term we could do away with the freezer DB entirely for validator-only nodes, but this change is much simpler and grants us some extra space in the short term. We can also roll it out gradually across our nodes by purging databases one by one, while keeping the Ansible config the same.

## Additional Info

We ignore a change from 2048 to 8192 if the user hasn't set the 8192 explicitly. We fire a debug log in the case where we do ignore:

```
DEBG Ignoring slots-per-restore-point config in favour of on-disk value, on_disk: 2048, config: 8192
```
2022-04-01 07:16:25 +00:00
Michael Sproul
41e7a07c51 Add lighthouse db command (#3129)
## Proposed Changes

Add a `lighthouse db` command with three initial subcommands:

- `lighthouse db version`: print the database schema version.
- `lighthouse db migrate --to N`: manually upgrade (or downgrade!) the database to a different version.
- `lighthouse db inspect --column C`: log the key and size in bytes of every value in a given `DBColumn`.

This PR lays the groundwork for other changes, namely:

- Mark's fast-deposit sync (https://github.com/sigp/lighthouse/pull/2915), for which I think we should implement a database downgrade (from v9 to v8).
- My `tree-states` work, which already implements a downgrade (v10 to v8).
- Standalone purge commands like `lighthouse db purge-dht` per https://github.com/sigp/lighthouse/issues/2824.

## Additional Info

I updated the `strum` crate to 0.24.0, which necessitated some changes in the network code to remove calls to deprecated methods.

Thanks to @winksaville for the motivation, and implementation work that I used as a source of inspiration (https://github.com/sigp/lighthouse/pull/2685).
2022-04-01 00:58:59 +00:00
Michael Sproul
c5212d0f98 Satisfy Clippy, remove non-tree-states code 2022-03-28 11:42:55 +11:00
Michael Sproul
648aba0332 Resolve some FIXMEs in the state cache 2022-03-18 15:02:44 +11:00
Michael Sproul
90ddaba1db Delete inaccurate block replay 2022-03-18 13:07:23 +11:00
Michael Sproul
ff649f0b26 Implement committee cache diffs 2022-03-15 17:08:14 +11:00
Michael Sproul
1a261e1d3b Implement database downgrade 2022-03-14 17:52:18 +11:00
Michael Sproul
b4c60807dd Implement DB upgrade migration 2022-03-10 15:31:32 +11:00
Michael Sproul
0ee31a0a69 Add lighthouse db command! 2022-03-08 13:39:24 +11:00
Michael Sproul
73af0b6282 CLI flags for state cache and compression level 2022-03-02 18:52:35 +11:00
Michael Sproul
64f0e3e13d New state pruning algorithm 2022-03-02 15:40:56 +11:00
Michael Sproul
ebe8e30171 Merge remote-tracking branch 'origin/unstable' into tree-states 2022-03-01 16:03:41 +11:00
Michael Sproul
98629ce741 Several changes
* Fix state cache pruning of finalized state from block map
* Update to latest `milhouse`
* Check beacon state diffs in EF tests
2022-03-01 15:54:14 +11:00
Michael Sproul
143cf59504 Beacon state diffs! 2022-02-25 19:35:45 +11:00
Michael Sproul
5e1f8a8480 Update to Rust 1.59 and 2021 edition (#3038)
## Proposed Changes

Lots of lint updates related to `flat_map`, `unwrap_or_else` and string patterns. I did a little more creative refactoring in the op pool, but otherwise followed Clippy's suggestions.

## Additional Info

We need this PR to unblock CI.
2022-02-25 00:10:17 +00:00
Michael Sproul
c88fcfed2b Implement ConsensusContext 2022-02-17 16:40:32 +11:00
Michael Sproul
1db0e32bfb Optimisations and bug fixes for state advance
This commit is reasonably performant on Prater!
2022-02-17 14:00:57 +11:00
Michael Sproul
e86cff2f8b Load all states relative to finalized state 2022-02-15 15:37:24 +11:00
Michael Sproul
b8709fdcab Fixups (still loading epoch boundary states) 2022-02-15 12:10:02 +11:00
Michael Sproul
5ff4868280 Merge remote-tracking branch 'michael/state-root-summary' into tree-states 2022-02-15 12:05:54 +11:00
Michael Sproul
f888a08f15 Revamp state advance, delete snapshot cache 2022-02-14 16:16:12 +11:00
Michael Sproul
c97f6dcc06 Persistent committee caches and exit cache 2022-02-11 17:41:43 +11:00
Michael Sproul
4340ba01b5 More tree fields, fix bugs 2022-02-09 17:42:58 +11:00
Michael Sproul
0c742aedff Use CoW 2022-02-08 09:48:48 +11:00
Michael Sproul
b2063c3e21 More vector 2022-01-28 15:45:44 +11:00
Michael Sproul
6714edf95b Merge remote-tracking branch 'origin/unstable' into tree-states 2022-01-25 18:59:11 +11:00
Michael Sproul
7245161fc2 Store all state roots on disk 2022-01-25 12:52:39 +11:00
Michael Sproul
a290a3c537 Add configurable block replayer (#2863)
## Issue Addressed

Successor to #2431

## Proposed Changes

* Add a `BlockReplayer` struct to abstract over the intricacies of calling `per_slot_processing` and `per_block_processing` while avoiding unnecessary tree hashing.
* Add a variant of the forwards state root iterator that does not require an `end_state`.
* Use the `BlockReplayer` when reconstructing states in the database. Use the efficient forwards iterator for frozen states.
* Refactor the iterators to remove `Arc<HotColdDB>` (this seems to be neater than making _everything_ an `Arc<HotColdDB>` as I did in #2431).

Supplying the state roots allow us to avoid building a tree hash cache at all when reconstructing historic states, which saves around 1 second flat (regardless of `slots-per-restore-point`). This is a small percentage of worst-case state load times with 200K validators and SPRP=2048 (~15s vs ~16s) but a significant speed-up for more frequent restore points: state loads with SPRP=32 should be now consistently <500ms instead of 1.5s (a ~3x speedup).

## Additional Info

Required by https://github.com/sigp/lighthouse/pull/2628
2021-12-21 06:30:52 +00:00
Michael Sproul
a43d5e161f Optimise balances cache in case of skipped slots (#2849)
## Proposed Changes

Remove the `is_first_block_in_epoch` logic from the balances cache update logic, as it was incorrect in the case of skipped slots. The updated code is simpler because regardless of whether the block is the first in the epoch we can check if an entry for the epoch boundary root already exists in the cache, and update the cache accordingly.

Additionally, to assist with flip-flopping justified epochs, move to cloning the balance cache rather than moving it. This should still be very fast in practice because the balances cache is a ~1.6MB `Vec`, and this operation is expected to only occur infrequently.
2021-12-13 23:35:57 +00:00
realbigsean
b22ac95d7f v1.1.6 Fork Choice changes (#2822)
## Issue Addressed

Resolves: https://github.com/sigp/lighthouse/issues/2741
Includes: https://github.com/sigp/lighthouse/pull/2853 so that we can get ssz static tests passing here on v1.1.6. If we want to merge that first, we can make this diff slightly smaller

## Proposed Changes

- Changes the `justified_epoch` and `finalized_epoch` in the `ProtoArrayNode` each to an `Option<Checkpoint>`. The `Option` is necessary only for the migration, so not ideal. But does allow us to add a default logic to `None` on these fields during the database migration.
- Adds a database migration from a legacy fork choice struct to the new one, search for all necessary block roots in fork choice by iterating through blocks in the db.
- updates related to https://github.com/ethereum/consensus-specs/pull/2727
  -  We will have to update the persisted forkchoice to make sure the justified checkpoint stored is correct according to the updated fork choice logic. This boils down to setting the forkchoice store's justified checkpoint to the justified checkpoint of the block that advanced the finalized checkpoint to the current one. 
  - AFAICT there's no migration steps necessary for the update to allow applying attestations from prior blocks, but would appreciate confirmation on that
- I updated the consensus spec tests to v1.1.6 here, but they will fail until we also implement the proposer score boost updates. I confirmed that the previously failing scenario `new_finalized_slot_is_justified_checkpoint_ancestor` will now pass after the boost updates, but haven't confirmed _all_ tests will pass because I just quickly stubbed out the proposer boost test scenario formatting.
- This PR now also includes proposer boosting https://github.com/ethereum/consensus-specs/pull/2730

## Additional Info
I realized checking justified and finalized roots in fork choice makes it more likely that we trigger this bug: https://github.com/ethereum/consensus-specs/pull/2727

It's possible the combination of justified checkpoint and finalized checkpoint in the forkchoice store is different from in any block in fork choice. So when trying to startup our store's justified checkpoint seems invalid to the rest of fork choice (but it should be valid). When this happens we get an `InvalidBestNode` error and fail to start up. So I'm including that bugfix in this branch.

Todo:

- [x] Fix fork choice tests
- [x] Self review
- [x] Add fix for https://github.com/ethereum/consensus-specs/pull/2727
- [x] Rebase onto Kintusgi 
- [x] Fix `num_active_validators` calculation as @michaelsproul pointed out
- [x] Clean up db migrations

Co-authored-by: realbigsean <seananderson33@gmail.com>
2021-12-13 20:43:22 +00:00
realbigsean
aa534f8989 Store execution block hash in fork choice (#2643)
* - Update the fork choice `ProtoNode` to include `is_merge_complete`
- Add database migration for the persisted fork choice

* update tests

* Small cleanup

* lints

* store execution block hash in fork choice rather than bool
2021-12-02 14:26:51 +11:00
Mark Mackey
5687c56d51 Initial merge changes
Added Execution Payload from Rayonism Fork

Updated new Containers to match Merge Spec

Updated BeaconBlockBody for Merge Spec

Completed updating BeaconState and BeaconBlockBody

Modified ExecutionPayload<T> to use Transaction<T>

Mostly Finished Changes for beacon-chain.md

Added some things for fork-choice.md

Update to match new fork-choice.md/fork.md changes

ran cargo fmt

Added Missing Pieces in eth2_libp2p for Merge

fix ef test

Various Changes to Conform Closer to Merge Spec
2021-12-02 14:26:50 +11:00
Michael Sproul
fca92c37ad Make BeaconState.balances a tree list! 2021-12-01 14:14:47 +11:00
Michael Sproul
4b808d3c72 More variable-variable lists 2021-11-26 13:13:46 +11:00
Michael Sproul
2dc6163043 Add API version headers and map_fork_name! (#2745)
## Proposed Changes

* Add the `Eth-Consensus-Version` header to the HTTP API for the block and state endpoints. This is part of the v2.1.0 API that was recently released: https://github.com/ethereum/beacon-APIs/pull/170
* Add tests for the above. I refactored the `eth2` crate's helper functions to make this more straight-forward, and introduced some new mixin traits that I think greatly improve readability and flexibility.
* Add a new `map_with_fork!` macro which is useful for decoding a superstruct type without naming all its variants. It is now used for SSZ-decoding `BeaconBlock` and `BeaconState`, and for JSON-decoding `SignedBeaconBlock` in the API.

## Additional Info

The `map_with_fork!` changes will conflict with the Merge changes, but when resolving the conflict the changes from this branch should be preferred (it is no longer necessary to enumerate every fork). The merge fork _will_  need to be added to `map_fork_name_with`.
2021-10-28 01:18:04 +00:00
Michael Sproul
aad397f00a Resolve Rust 1.56 lints and warnings (#2728)
## Issue Addressed

When compiling with Rust 1.56.0 the compiler generates 3 instances of this warning:

```
warning: trailing semicolon in macro used in expression position
   --> common/eth2_network_config/src/lib.rs:181:24
    |
181 |                     })?;
    |                        ^
...
195 |         let deposit_contract_deploy_block = load_from_file!(DEPLOY_BLOCK_FILE);
    |                                             ---------------------------------- in this macro invocation
    |
    = note: `#[warn(semicolon_in_expressions_from_macros)]` on by default
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #79813 <https://github.com/rust-lang/rust/issues/79813>
    = note: this warning originates in the macro `load_from_file` (in Nightly builds, run with -Z macro-backtrace for more info)
```

This warning is completely harmless, but will be visible to users compiling Lighthouse v2.0.1 (or earlier) with Rust 1.56.0 (to be released October 21st). It is **completely safe** to ignore this warning, it's just a superficial change to Rust's syntax.

## Proposed Changes

This PR removes the semi-colon as recommended, and fixes the new Clippy lints from 1.56.0
2021-10-19 00:30:42 +00:00
Paul Hauner
e2d09bb8ac Add BeaconChainHarness::builder (#2707)
## Issue Addressed

NA

## Proposed Changes

This PR is near-identical to https://github.com/sigp/lighthouse/pull/2652, however it is to be merged into `unstable` instead of `merge-f2f`. Please see that PR for reasoning.

I'm making this duplicate PR to merge to `unstable` in an effort to shrink the diff between `unstable` and `merge-f2f` by doing smaller, lead-up PRs.

## Additional Info

NA
2021-10-14 02:58:10 +00:00
Michael Sproul
ed1fc7cca6 Fix I/O atomicity issues with checkpoint sync (#2671)
## Issue Addressed

This PR addresses an issue found by @YorickDowne during testing of v2.0.0-rc.0.

Due to a lack of atomic database writes on checkpoint sync start-up, it was possible for the database to get into an inconsistent state from which it couldn't recover without `--purge-db`. The core of the issue was that the store's anchor info was being stored _before_ the `PersistedBeaconChain`. If a crash occured so that anchor info was stored but _not_ the `PersistedBeaconChain`, then on restart Lighthouse would think the database was unitialized and attempt to compare-and-swap a `None` value, but would actually find the stale info from the previous run.

## Proposed Changes

The issue is fixed by writing the anchor info, the split point, and the `PersistedBeaconChain` atomically on start-up. Some type-hinting ugliness was required, which could possibly be cleaned up in future refactors.
2021-10-05 03:53:17 +00:00
Paul Hauner
fe52322088 Implement SSZ union type (#2579)
## Issue Addressed

NA

## Proposed Changes

Implements the "union" type from the SSZ spec for `ssz`, `ssz_derive`, `tree_hash` and `tree_hash_derive` so it may be derived for `enums`:

https://github.com/ethereum/consensus-specs/blob/v1.1.0-beta.3/ssz/simple-serialize.md#union

The union type is required for the merge, since the `Transaction` type is defined as a single-variant union `Union[OpaqueTransaction]`.

### Crate Updates

This PR will (hopefully) cause CI to publish new versions for the following crates:

- `eth2_ssz_derive`: `0.2.1` -> `0.3.0`
- `eth2_ssz`: `0.3.0` -> `0.4.0`
- `eth2_ssz_types`: `0.2.0` -> `0.2.1`
- `tree_hash`: `0.3.0` -> `0.4.0`
- `tree_hash_derive`: `0.3.0` -> `0.4.0`

These these crates depend on each other, I've had to add a workspace-level `[patch]` for these crates. A follow-up PR will need to remove this patch, ones the new versions are published.

### Union Behaviors

We already had SSZ `Encode` and `TreeHash` derive for enums, however it just did a "transparent" pass-through of the inner value. Since the "union" decoding from the spec is in conflict with the transparent method, I've required that all `enum` have exactly one of the following enum-level attributes:

#### SSZ

-  `#[ssz(enum_behaviour = "union")]`
    - matches the spec used for the merge
-  `#[ssz(enum_behaviour = "transparent")]`
    - maintains existing functionality
    - not supported for `Decode` (never was)
    
#### TreeHash

-  `#[tree_hash(enum_behaviour = "union")]`
    - matches the spec used for the merge
-  `#[tree_hash(enum_behaviour = "transparent")]`
    - maintains existing functionality

This means that we can maintain the existing transparent behaviour, but all existing users will get a compile-time error until they explicitly opt-in to being transparent.

### Legacy Option Encoding

Before this PR, we already had a union-esque encoding for `Option<T>`. However, this was with the *old* SSZ spec where the union selector was 4 bytes. During merge specification, the spec was changed to use 1 byte for the selector.

Whilst the 4-byte `Option` encoding was never used in the spec, we used it in our database. Writing a migrate script for all occurrences of `Option` in the database would be painful, especially since it's used in the `CommitteeCache`. To avoid the migrate script, I added a serde-esque `#[ssz(with = "module")]` field-level attribute to `ssz_derive` so that we can opt into the 4-byte encoding on a field-by-field basis.

The `ssz::legacy::four_byte_impl!` macro allows a one-liner to define the module required for the `#[ssz(with = "module")]` for some `Option<T> where T: Encode + Decode`.

Notably, **I have removed `Encode` and `Decode` impls for `Option`**. I've done this to force a break on downstream users. Like I mentioned, `Option` isn't used in the spec so I don't think it'll be *that* annoying. I think it's nicer than quietly having two different union implementations or quietly breaking the existing `Option` impl.

### Crate Publish Ordering

I've modified the order in which CI publishes crates to ensure that we don't publish a crate without ensuring we already published a crate that it depends upon.

## TODO

- [ ] Queue a follow-up `[patch]`-removing PR.
2021-09-25 05:58:36 +00:00
Michael Sproul
9667dc2f03 Implement checkpoint sync (#2244)
## Issue Addressed

Closes #1891
Closes #1784

## Proposed Changes

Implement checkpoint sync for Lighthouse, enabling it to start from a weak subjectivity checkpoint.

## Additional Info

- [x] Return unavailable status for out-of-range blocks requested by peers (#2561)
- [x] Implement sync daemon for fetching historical blocks (#2561)
- [x] Verify chain hashes (either in `historical_blocks.rs` or the calling module)
- [x] Consistency check for initial block + state
- [x] Fetch the initial state and block from a beacon node HTTP endpoint
- [x] Don't crash fetching beacon states by slot from the API
- [x] Background service for state reconstruction, triggered by CLI flag or API call.

Considered out of scope for this PR:

- Drop the requirement to provide the `--checkpoint-block` (this would require some pretty heavy refactoring of block verification)


Co-authored-by: Diva M <divma@protonmail.com>
2021-09-22 00:37:28 +00:00
Michael Sproul
9c785a9b33 Optimize process_attestation with active balance cache (#2560)
## Proposed Changes

Cache the total active balance for the current epoch in the `BeaconState`. Computing this value takes around 1ms, and this was negatively impacting block processing times on Prater, particularly when reconstructing states.

With a large number of attestations in each block, I saw the `process_attestations` function taking 150ms, which means that reconstructing hot states can take up to 4.65s (31 * 150ms), and reconstructing freezer states can take up to 307s (2047 * 150ms).

I opted to add the cache to the beacon state rather than computing the total active balance at the start of state processing and threading it through. Although this would be simpler in a way, it would waste time, particularly during block replay, as the total active balance doesn't change for the duration of an epoch. So we save ~32ms for hot states, and up to 8.1s for freezer states (using `--slots-per-restore-point 8192`).
2021-09-03 07:50:43 +00:00
Michael Sproul
10945e0619 Revert bad blocks on missed fork (#2529)
## Issue Addressed

Closes #2526

## Proposed Changes

If the head block fails to decode on start up, do two things:

1. Revert all blocks between the head and the most recent hard fork (to `fork_slot - 1`).
2. Reset fork choice so that it contains the new head, and all blocks back to the new head's finalized checkpoint.

## Additional Info

I tweaked some of the beacon chain test harness stuff in order to make it generic enough to test with a non-zero slot clock on start-up. In the process I consolidated all the various `new_` methods into a single generic one which will hopefully serve all future uses 🤞
2021-08-30 06:41:31 +00:00
realbigsean
303deb9969 Rust 1.54.0 lints (#2483)
## Issue Addressed

N/A

## Proposed Changes

- Removing a bunch of unnecessary references
- Updated `Error::VariantError` to `Error::Variant`
- There were additional enum variant lints that I ignored, because I thought our variant names were fine
- removed `MonitoredValidator`'s `pubkey` field, because I couldn't find it used anywhere. It looks like we just use the string version of the pubkey (the `id` field) if there is no index

## Additional Info



Co-authored-by: realbigsean <seananderson33@gmail.com>
2021-07-30 01:11:47 +00:00
realbigsean
a3a7f39b0d [Altair] Sync committee pools (#2321)
Add pools supporting sync committees:
- naive sync aggregation pool
- observed sync contributions pool
- observed sync contributors pool
- observed sync aggregators pool

Add SSZ types and tests related to sync committee signatures.

Co-authored-by: Michael Sproul <michael@sigmaprime.io>
Co-authored-by: realbigsean <seananderson33@gmail.com>
2021-07-15 00:52:02 +00:00
Michael Sproul
371c216ac3 Use read_recursive locks in database (#2417)
## Issue Addressed

Closes #2245

## Proposed Changes

Replace all calls to `RwLock::read` in the `store` crate with `RwLock::read_recursive`.

## Additional Info

* Unfortunately we can't run the deadlock detector on CI because it's pinned to an old Rust 1.51.0 nightly which cannot compile Lighthouse (one of our deps uses `ptr::addr_of!` which is too new). A fun side-project at some point might be to update the deadlock detector.
* The reason I think we haven't seen this deadlock (at all?) in practice is that _writes_ to the database's split point are quite infrequent, and a concurrent write is required to trigger the deadlock. The split point is only written when finalization advances, which is once per epoch (every ~6 minutes), and state reads are also quite sporadic. Perhaps we've just been incredibly lucky, or there's something about the timing of state reads vs database migration that protects us.
* I wrote a few small programs to demo the deadlock, and the effectiveness of the `read_recursive` fix: https://github.com/michaelsproul/relock_deadlock_mvp
* [The docs for `read_recursive`](https://docs.rs/lock_api/0.4.2/lock_api/struct.RwLock.html#method.read_recursive) warn of starvation for writers. I think in order for starvation to occur the database would have to be spammed with so many state reads that it's unable to ever clear them all and find time for a write, in which case migration of states to the freezer would cease. If an attack could be performed to trigger this starvation then it would likely trigger a deadlock in the current code, and I think ceasing migration is preferable to deadlocking in this extreme situation. In practice neither should occur due to protection from spammy peers at the network layer. Nevertheless, it would be prudent to run this change on the testnet nodes to check that it doesn't cause accidental starvation.
2021-07-12 07:31:26 +00:00
Michael Sproul
b4689e20c6 Altair consensus changes and refactors (#2279)
## Proposed Changes

Implement the consensus changes necessary for the upcoming Altair hard fork.

## Additional Info

This is quite a heavy refactor, with pivotal types like the `BeaconState` and `BeaconBlock` changing from structs to enums. This ripples through the whole codebase with field accesses changing to methods, e.g. `state.slot` => `state.slot()`.


Co-authored-by: realbigsean <seananderson33@gmail.com>
2021-07-09 06:15:32 +00:00